JP2573476B2 - Heat stable polyester composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant thermoplastic polyester composition having improved moldability, mechanical properties, heat resistance during melting or long-term heat aging, and resistance to discoloration. More specifically, the present invention relates to a thermoplastic polyester composition comprising a flame-retardant polyalkylene terephthalate resin blended with a low-molecular-weight polyethylene wax that does not have moldability by itself.

[0002]

BACKGROUND OF THE INVENTION High molecular weight polyesters or copolymerized polyesters composed of glycol and terephthalic acid or isophthalic acid have excellent mechanical properties, electrical properties, moldability, etc., and are therefore used as engineering plastics. Used for a wide range of applications. However, these thermoplastic polyesters are inherently flammable and their uses are limited. Therefore, various attempts have been made to make the flame retardant. Conventionally, in order to make a thermoplastic polyester flame-retardant, an organic halogen compound such as decabromodiphenyl ether, brominated polycarbonate, brominated cyanuric acid ester compound, or brominated epoxy compound is blended as a flame retardant. Further, in this case, by using a flame retardant auxiliary such as a metal oxide or hydroxide such as antimony trioxide, antimony halide, aluminum hydroxide, or magnesium hydroxide, a more excellent flame retardant effect can be obtained. It is also known. However, these compounds are by no means preferable from the viewpoint of heat stability of the resin. That is, the above-described halogen compound is decomposed little by little by heat or light to generate halogen radicals, and then a hydrogen abstraction reaction is performed to generate hydrogen halide. This radical or hydrogen halide promotes radical decomposition, hydrolysis, transesterification and the like of the polyester resin, and causes deterioration of the resin. On the other hand, an inorganic compound represented by antimony trioxide also essentially acts as a catalyst for hydrolysis and transesterification, and thus adversely affects the heat resistance of the polyester resin. Therefore, if the resin to which these flame retardants are added stays in the machine at the time of extrusion or molding, or if heat aging is performed for a long time, the mechanical properties of the resin become remarkable. Therefore, if the adverse effect on the deterioration of the resin can be suppressed without impairing the flame-retardant imparting properties of these substances, not only can the application of the resin composition be expanded, but also the conventional resin composition can be applied due to lack of heat resistance stability. Hot liner type molding, which is more difficult and more advantageous in resource saving, is also possible.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to improve these points, and as a result, a low-molecular-weight polyethylene wax having no moldability by itself has been added to the above-mentioned flame retardants and flame retardant auxiliaries. By preliminarily kneading the mixture at its melting point or higher, and pre-treating it after cooling and pulverizing, the polyester is blended with a flame retardant and a flame retardant auxiliary, so that the heat resistance, moldability, mechanical properties, etc. resulting from the deterioration of the resin Was found to be significantly improved, and the present invention was reached. That is, the present invention provides an organic halogen compound-based flame retardant (2 to 50% by weight based on the total composition),
A flame retardant aid (2 to 20% by weight based on the total composition) is mixed with a polyethylene wax (0.5 to 100% by weight based on the organic halogen compound-based flame retardant and the flame retardant aid) which does not have moldability by itself. It is a heat-resistant and stable polyester composition containing a polyethylene wax which has no moldability by itself, is kneaded at a temperature higher than the melting point of the polyethylene wax, cooled and pulverized, and contains an inorganic filler (2 to 50% by weight based on the total composition). ADVANTAGE OF THE INVENTION According to the composition of this invention, the moldability (release property) is excellent, and especially the heat stability, discoloration resistance, and mechanical properties of a thermoplastic polyester resin during melting or long-term heat aging are dramatically improved. Can be done. Such effects of the present invention are not observed with stabilizers generally used in conventional polyester compositions. This fact is based on the fact that low molecular weight polyethylene wax, which does not have moldability by itself, is blended with thermoplastic polyester resin to suppress radical decomposition, hydrolysis, transesterification, etc. caused by flame retardants, flame retardant auxiliaries, etc. This is considered to be due to prevention of deterioration of the resin.

In the present invention, low molecular weight (usually, molecular weight of about 6000 or less) polyethylene, which is not itself moldable, so-called polyethylene wax is used as an additive.
This is blended in a specific method as described below. As is well known, polyethylene wax is produced by pyrolysis of polyethylene resin or polymerization of ethylene.
In the polymerization of ethylene, a small amount of a comonomer such as propylene, vinyl acetate, acrylic acid, or acrylate ester may be blended. For the purpose of the present invention, a polyethylene wax obtained by a thermal decomposition method is preferred in view of dispersibility since it has some polar groups. These polyethylene waxes can be used alone or in combination of two or more. The amount of low molecular weight polyethylene wax that does not have moldability by itself is 0.5 to 0.5% for flame retardants and flame retardant auxiliaries.
It is appropriately selected in the range of 100% by weight. Preferably 2
50% by weight. Thus, a very small amount is sufficient for the entire polyester composition, for example 5
The effect is also observed at less than 1% by weight, more preferably at most 1% by weight.

The composition of the present invention further comprises antioxidants such as hindered phenols, hindered amines and various derivatives thereof; aromatic phosphites such as triphenyl phosphite and tricresyl phosphite, and tridecyl phosphite. And a phosphorus-containing stabilizer such as an alkyl phosphite or a phosphonate; and commonly used antioxidants, ultraviolet stabilizers, hydrolysis stabilizers, and heat stabilizers. In the polyester composition of the present invention, glass fibers, carbon fibers and other reinforcing agents and pigments, dyes, talc, fillers such as potassium titanate, lubricants, antistatic agents, crystal nucleating agents,
Plasticizers, blowing agents and the like may be added. The amount of the inorganic filler such as glass fiber is generally 2 to 50% by weight based on the total composition.
It is.

As the flame retardant used in the present invention, there are generally used organic halogen compounds, phosphorus compounds and the like, and particularly, organic bromine compounds are preferable. As an example, a bromine compound of diphenyl ether, a bromine 5 to 10-substituted compound of aromatic ring hydrogen of ethylene bisphenyl ether, or an aromatic carbonate derived from bisphenol A or the like, a monomer of an epoxy compound thereof or a polymer thereof or the like. Brominated products, brominated polystyrene oligomers, brominated cyanuric acid ester compounds, and the like. As the addition amount of the flame retardant increases, the mechanical properties of the composition decrease. Therefore, it is preferable that the addition amount be as small as possible. The amount of addition
It is generally 2 to 50% by weight, preferably 3 to 20% by weight, based on the total composition. Although there is no particular limitation on the flame retardant aid, examples thereof include antimony trioxide, aluminum hydroxide, and magnesium hydroxide. The addition amount of these flame retardant aids is generally 2 to 20% by weight based on the total composition. In the present invention, two or more of these flame retardants can be used in combination. Examples include decabromodiphenyl ether and brominated polycarbonate, and decabromodiphenyl ether and brominated epoxy compounds. The brominated cyanuric acid ester compound is generally used as a flame retardant, but when used in combination with another flame retardant, a synergistic heat resistance effect upon melting and an effect as a stabilizer are also recognized. The amount added at this time is not particularly limited. The brominated cyanuric ester compound suitable for use in the present invention comprises a brominated cyanuric ester compound having a triazine ring represented by the following general formula alone or a mixture thereof.

[0007]

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N: degree of polymerization R: H, R ₁ , R ₂ R ₁ :

[0009]

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A + b + c + d ≦ 8 Z: alkylidene, alkylene, —SO ₂ −, —SO—, —S—,
-O- or two phenylene groups are linked.

R ₃ : H, a lower alkyl group (halogen is preferably chlorine or bromine), a halogenated lower alkyl group (halogen is preferably chlorine or bromine) R ₂ :

[0012]

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At least one of e + g ≦ 5 R is R ₁ , and the terminal of R ₁ is H, OH or R ₂ .

The polyester resin used in the present invention is obtained by using glycerides and terephthalic acid or a derivative thereof as an acid component. These components can be modified with other glycols or dicarboxylic acids. . Examples of the dicarboxylic acid used for the modification of the polyester include isophthalic acid, alkyl-substituted phthalic acids such as naphthalenedicarboxylic acid, aromatic dicarboxylic acids, succinic acid, adipic acid, azelaic acid, dodecanoic acid, and aliphatic or cyclohexanedicarboxylic acid. Alicyclic dicarboxylic acids and the like; Examples of the glycol to be modified include neopentyl glycol, 1,4-dimethylolcyclohexane, 2-methylpentanol, and aliphatic or alicyclic glycols such as bisphenol A. One or more of these modifying components can be used. Preferred polyester resin used in the present invention is polyethylene terephthalate,
It is a polyalkylene terephthalate resin such as polybutylene terephthalate. One or more of these polyester resins may be mixed. Particularly, a mixed system of polyethylene terephthalate and polybutylene terephthalate is preferable.
The polyester used in the present invention has an intrinsic viscosity of o-
At 8% concentration in chlorophenol at 23 ℃
Those having 0.4 dl / g, preferably 0.4 to 1.5 dl / g, particularly preferably 0.7 to 1.2 dl / g.

The present invention is characterized by kneading a low molecular weight polyethylene wax which does not have a moldability by itself with a flame retardant and a flame retardant auxiliary as a pretreatment.
In this case, use a Henschel mixer with a jacket, a Banbury mixer, or an extruder to knead the mixture at or above the melting point.
After cooling, crushing is performed, and the obtained blend is blended with a polyester resin together with other additives, and then, similarly to a general method, may be melt-kneaded with a heated extruder and then extruded into pellets. . It is also possible to pre-treat not only the flame retardant and the flame retardant auxiliary but also other additives with a low molecular weight polyethylene wax which does not have moldability by itself as described above.

[0016]

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. Examples 1 to 5 and Comparative Examples 1 to 4 Components of each composition shown in Table 1 using polybutylene terephthalate (PBT) having an intrinsic viscosity of 0.80 dl / g and polyethylene terephthalate (PET) having an intrinsic viscosity of 0.68 dl / g. Was mixed. At that time, in the examples, the flame retardant and the flame retardant auxiliary were pretreated with low molecular weight polyethylene by the following method before use. That is, a predetermined amount of low molecular weight polyethylene, an organic halogen compound of a flame retardant, and antimony trioxide of a flame retardant auxiliary were kneaded at a temperature higher than the melting temperature of the low molecular weight polyethylene by a jacketed Henschel mixer heated with steam. After sufficient kneading, the steam was switched to cooling water, cooled and pulverized to obtain a pretreated sample. The mixture mixed in the specified amount shown in Table 1 is 240
The pellets were extruded with a 65 mm single extruder heated to ~ 250 ° C. After drying the obtained pellets with a hot air drier 2
ASTM tensile test pieces were molded on an injection molding machine set at a cylinder temperature of 60 ° C. Molding was performed in a normal molding cycle (injection time 20 seconds + cooling time 10 seconds) with 0 minute,
After the sample was kept in the molding machine for another 30 minutes, it was molded, and the heat stability was compared. The test pieces were placed in a hot-air dryer maintained at 200 ° C., and the tensile strengths were compared by long-term heat aging. The discoloration resistance during melting was compared with the discoloration degree ΔE. That is, Hunter's color system L, a, b of the test piece was measured with a digital colorimeter (ND504AA, manufactured by Nippon Denshoku Industries Co., Ltd.)
And the discoloration degree ΔE was calculated according to the following equation. Δ
The smaller the E value, the better the discoloration resistance.

[0017]

(Equation 1)

L ₀ , a ₀ , b ₀ : residence time of molding machine 0 minutes L, a, b: residence time of molding machine 30 minutes The results are shown in Tables 1 and 2. In addition, the numerical values of the compositions in Table 1 are all compositions except the pretreatment amount of polyethylene (PE).
Parts by weight per 100 parts by weight.

[0019]

[Table 1]

[0020]

[Table 2]

The molding temperature of the test piece was set at a cylinder temperature of 240 ° C. Example 6 The composition, the production method, and the procedure were the same as those of Examples 1 to 5 except that the low-molecular-weight polyethylene (molecular weight 5,000) produced by a different polymerization method was used instead of the low-molecular-weight polyethylene produced by the pyrolysis method (molecular weight 5000). The evaluation was performed in the same manner as in Example 1. Table 3 shows the results.

[0022]

[Table 3]

Examples 7 to 8 and Comparative Example 5 In the formulation of Example 2, polyethylene having a different molecular weight was used as the polyethylene, and the preparation of the sample was similarly performed using a 28 mm twin screw extruder. Table 4 shows the results.

[0024]

[Table 4]

The low molecular weight polyethylenes having a molecular weight of 1500 and 5000 are pyrolysis products.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 23:06)

Claims (6)

(57) [Claims] 1. An organic halogen compound flame retardant (2 to 50% by weight based on the total composition), a flame retardant auxiliary (2 to 50% by weight based on the total composition)
20% by weight) and the melting point of polyethylene wax which does not have moldability by itself (0.5 to 100% by weight based on organic halogen compound flame retardant and flame retardant aid). A mixture kneaded at the above temperature, cooled and pulverized, and an inorganic filler (2- to the total composition)
50% by weight). 2. The composition according to claim 1, wherein the thermoplastic polyester resin is a polyalkylene terephthalate resin. 3. The composition according to claim 2, wherein the polyalkylene terephthalate resin is polybutylene terephthalate. 4. The composition according to claim 1, wherein the flame retardant aid is an inorganic compound. 5. The organic halogen compound-based flame retardant is decabromodiphenyl ether, brominated polycarbonate, brominated cyanuric ester compound, brominated epoxy compound or a mixture thereof.
A composition according to any of the preceding clauses. 6. The composition according to claim 1, wherein the inorganic filler is glass fiber.